The overall objective of this project is to gain a better understanding of the biology of pathogenic streptococci in order to control infections caused by these organisms and to prevent their complications (e.g. rheumatic fever and acute nephritis). Broad objectives will include studies of 1) Streptococcal bacteriophages, genetic variation and nucleases, 2) Streptococcal bacteriocins, 3) Specific antigens, antibodies and cellular responses related to Group A streptococci, 4) Group B streptococci.